SANTA CLARA, Calif. -- In the aftermath of their NFC Championship Game win against the Detroit Lions, the San Francisco 49ers first felt a sense of relief followed by joy and then, after watching the tape, at least a little bit of disappointment.
For all of coach Kyle Shanahan's tenure since taking over in 2017, the Niners have prided themselves on playing at full speed all the time. But on multiple plays in the 34-31 win against the Lions, Shanahan and his staff spotted issues with effort.
It was a jarring sight.
"Collectively as a team, I can tell you as a defense it's unacceptable," defensive coordinator Steve Wilks said Friday. "We talked about that. I wish I could tell these guys on Play 4, on Play 27, this is what's going to happen. You don't know. So we've got to make sure that we play every down as if it's going to be the difference in the ballgame. And you could see on those particular plays, it wasn't to our standard. Those guys understand and know that, and quite honestly it was embarrassing."
Shanahan pointed to two or three plays in the game that he said were "not our culture." That culture is rooted in the ethos of past defensive coordinators such as Robert Saleh, who preached an "all gas, no brakes" mentality, and DeMeco Ryans, who insisted on "swarming" opposing ball carriers.
For most of this season, effort has not been an issue. But it did show up against the Lions and contributed to San Francisco's 24-7 halftime deficit. Shanahan called out his defense for what he considered poor backside pursuit on run plays against the Lions.
That was most evident on Detroit running back Jahmyr Gibbs' 15-yard touchdown run when defensive end Chase Young could be seen jogging toward Gibbs, who cuts back in front of Young for the score. There was a similar problem in the secondary on Lions wide receiver Jameson Williams' 42-yard touchdown run.
"They were expecting someone else to make the tackle," Shanahan said. "Whenever you're expecting someone else to make the tackle, bad things happen. "
Those bad things have added up for the Niners defense in the postseason. Through two games against the Green Bay Packers and Lions, San Francisco has given up an average of 26 points and 159 rushing yards per game, a significant uptick from the 17.5 points and 89.7 rushing yards it yielded in the regular season.
On Friday, general manager John Lynch cited his playing career with the Tampa Bay Buccaneers' dominant defense of the late 1990s and early 2000s as the standard of what he expects from a Niners defense that has consistently been among the best in the NFL over the past five seasons.
"Effort is a nonnegotiable," Lynch said. "Those things have been addressed. You've got one game. I really would be shocked if we saw that again."
That one game just happens to be the one the Niners have been longing to return to for most of the past four years. The 49ers leave for Las Vegas on Sunday to finish preparations for Super Bowl LVIII against the Kansas City Chiefs, the same team that defeated them in Super Bowl LIV.
That game still lingers in the minds of the 49ers who remain on the roster and have bad memories of San Francisco losing a 10-point fourth-quarter lead. On Thursday, defensive end Nick Bosa said the Niners are playing with the same intensity as that team but with the caveat that it's not as consistent as it was then.
"I'm going to just relay to the guys that there has to be a different level of effort and intensity and unselfishness that you have to get to for every single snap that you're in there," Bosa said.
Linebacker Fred Warner echoed that sentiment, noting that he was left "scarred for life" by the previous loss to the Chiefs while also extolling the importance of playing with maximum energy for every minute of the season's final game.
"The standard has been what it has been for as long as I've been here, and we've relied heavily on winning games on defense, holding teams to minimal points, suffocating teams, dictating how the game's going to go based off how we go," Warner said. "And that hasn't been the case the last two games, and that's for a bunch of different reasons. ... But we have a great opportunity to correct that and make sure that we give our best performance in the Super Bowl. I think that's exactly where our mindset is at."